Process for the manufacture of fluorinated olefins

ABSTRACT

In certain aspects, the present invention relates to methods for increasing the cost efficiency and safety of the hydrogenation of a fluorinated olefin by controlling the reaction conditions and parameters. In further aspects, the hydrogenation reaction is provided in a two stage reaction wherein the reactant amounts, temperature and other parameters are controlled such that the conversion percentage, selectivity, and reaction parameters are all within commercially acceptable levels.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a division of U.S. application Ser. No.13/827,302, filed Mar. 14, 2013 which is herein incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to processes for producing haloalkenes,particularly, though not exclusively, 2,3,3,3-tetrafluoropropane(HFO-1234yf) and/or 1,2,3,3,3-pentafluoropropene (HFO-1225ye).

BACKGROUND OF THE INVENTION

Chlorine-containing compounds, such as chlorofluorocarbons (CFCs), havebeen employed as refrigerants, foam blowing agents, cleaning agents,solvents, heat transfer media, sterilants, aerosol propellants,dielectrics, fire extinguishing agents, and power cycle working fluids.Such chlorine-containing compounds have proven to be detrimental to theEarth's ozone layer. Many of the hydrofluorocarbons (HFCs), used as thesubstitutes of CFCs, have been found to contribute to global warming.For these reasons, there is a worldwide effort to develop new compoundsthat are more environmentally benign while at the same time being aseffective, or more effective, from a performance standpoint.

Applicants have come to appreciate that 1,1,1,2,3-pentafluoropropene(HFO-1225ye) and 1,1,1,2-tetrafluoropropene (HFO-1234yf) are each usefulin one or more of the above mentioned applications. Accordingly,compositions containing either or both fluorinated olefins are among thematerials being developed for such use.

Methods for producing HFO-1234yf and HFO-1225ye are known. In oneexample, it is known that hexafluoropropylene (HFP) can be hydrogenatedto produce 1,1,1,2,3,3-hexafluoropropane (HFC-236ea). HFC-236ea is thenused as a reactant in a dehydrogenation reaction to produce HFO-1225ye.It is further known that HFO-1225ye can be hydrogenated to produce1,1,1,2,3-pentafluoropropane (HFC-245eb) and that HFC-245eb can then bedehydrofluorinated to produce HFO-1234yf.

U.S. Pat. No. 8,013,194, the contents of which are incorporated byreference herein, further provides that HFO-1225ye and HFO-1234yf can beproduced in a single facility. Most notably, it was realized that thehydrogenation of HFP can yield both HFC-236ea and HFC-245eb and thatthese two products can be simultaneously dehydrofluorinated to produceHFO-1225ye and HFO-1234yf, respectively. Processing conditions aretaught to be adjustable, so as to favor the selective conversion of onehydrofluoroolefin over the other. Catalysts that may be used for suchreactions were taught to include metal catalysts, even more preferablyone or more transition metal-based catalysts (including in certainpreferred embodiments transition metal halide catalysts), such as FeCl₃,chromiumoxyfluoride, Ni (including Ni mesh), NiCl₂, CrF₃, and mixturesthereof, supported or in bulk. Other catalysts include carbon-supportedcatalysts, antimony-based catalysts (such as SbCl₅), aluminum-basedcatalyst (such as AlF₃, Al₂O₃, and fluorinated Al₂O₃), palladium-basedcatalysts, platinum-based catalysts, rhodium-based catalysts andruthenium-based catalysts, including combinations thereof.

Other examples of methods for the production of HFO-1225ye andHFO-1234yf are set forth in, at least, U.S. Pat. No. 7,560,602, which isassigned to the assignee of the present invention and is incorporatedherein by reference. This patent discloses a similar dehydrohalogenationprocess for producing 2,3,3,3-tetrafluoropropene (1234yf) and1,1,1,2,3-pentafluoropropene (HFO-1225ye) by catalyticdehydrofluorination of 1,1,1,2,3-pentafluoropropane (245eb) and1,1,1,2,3,3-hexafluoropropane (HFC-236ea), respectively. Preferreddehydrohalogenation catalysts include fluorinated chromium oxidecatalysts, aluminum fluoride catalysts, ferric fluoride catalysts,mixtures of magnesium fluoride and aluminum fluoride catalysts,nickel-based catalysts, carbon based catalysts, and combinationsthereof.

Alternative agents for such dehydrohalogenation reactions are alsoknown. U.S. Patent Application Publication No. 20100029997, for example,teaches the production of hydrofluoroolefins (e.g. HFO-1234yf) bydehydrohalogenating HFC-245eb by contacting it to potassium hydroxide(KOH), sodium hydroxide (NaOH), Ca(OH)₂, CaO, and combinations thereof.While, in certain embodiments, dehydrohalogenation agents include KOH,alternative agents also include LiOH, Mg(OH)₂ and NaOH.

Applicants have come to appreciate that in commercial production orlarge scale production of fluorocarbons, such as HFO-1234yf andHFO-1225ye, reactions utilizing hydrogen present significant challenges.Hydrogenation reactions are typically highly exothermic, which createschallenges for thermal management of a large reactor system,particularly at a commercial or large manufacturing scale. Also, theability to effectively utilize hydrogen to achieve a high conversion ofthe starting material is critical to an economic process. Safety indealing with hydrogenation processes is also critical, as thetemperatures of the reaction can easily reach extremely high, andunsafe, levels.

SUMMARY OF THE INVENTION

The present invention relates, at least in part, to methods ofincreasing the cost efficiency and improving the safety for halogenationproduction of a fluorinated alkane using a fluorinated olefin startingreagent, and in further embodiments to the use of such alkanes in theproduction of desired fluorinated olefin products.

In certain non-limiting embodiments, the present invention relates tomethods for producing at least one halogenated alkane by first providinga starting material stream comprising at least one halogenated alkeneaccording to Formula (I)(CX_(n)Y_(3−n))(CR¹ _(a)R² _(b))_(z)CX═CH_(m)X_(2−m)and at least one halogenated alkane according to Formula (II)(CX_(n)Y_(3−n))(CR¹ _(a)R² _(b))_(z)CHXCH_(m+1)X_(2−m),where: each X is independently Cl, F, I or Br, provided that at leasttwo Xs are F; each Y is independently H, Cl, F, I or Br; each R¹ isindependently H, Cl, F, I, Br or unsubstituted or halogen substitutedmethyl or ethyl radical; each R₂ is independently H, Cl, F, I, Br orunsubstituted or halogen substituted methyl or ethyl radical; n is 1, 2or 3; a and b are each 0, 1 or 2, provided that a+b=2; m is 0, 1 or 2;and z is 0, 1, 2 or 3. In certain non-limiting aspects, the ratio of thehalogenated alkene to the halogenated alkane of the starting materialfeed stream is from about 1:3 to about 1:25, in further aspects fromabout 1:6 to about 1:22, and in even further aspects from about 1:8 toabout 1:20.

The starting material is then hydrogenated to produce an intermediatematerial stream by contacting said starting material stream with areducing agent (e.g. H₂) such that at least a portion of the alkene ofFormula I is converted to the alkane of Formula II. In certainnon-limiting aspects, the hydrogenation step results in a percentconversion of the alkene in the starting material feed stream of betweenabout 25 wt. % and about 75 wt. %, in certain preferred embodimentsbetween about 35 wt. % and about 65 wt. %, in further preferredembodiments between about 40 wt. % and about 60 wt. %, and in evenfurther preferred embodiments between about 45 wt. % and about 55 wt. %.

The intermediate product stream is then separated into at least a firstintermediate product stream comprising the alkene of formula I and thealkane of formula II and a second intermediate product stream comprisingthe alkene of formula I and the alkane of formula II. The firstintermediate product stream is then recycled to the first reactor. Incertain embodiments, prior to being recycled the first intermediateproduct stream is mixed with additional starting material (i.e.additional halogenated alkene), thereby, adjusting the ratio of thefluorinated alkene to the fluorinated alkane. In certain non-limitingaspects, the additional starting material is provided such that theresulting ratio of the fluorinated alkene to the fluorinated alkane inthe first intermediate product stream is from about 1:3 to about 1:25,in certain preferred embodiments the ratio is from about 1:6 to about1:22, and in further preferred embodiments the ratio is from about 1:8to about 1:20.

The second intermediate product stream is then further hydrogenated in asecond reactor to produce a final product stream. In certainnon-limiting embodiments, the final product stream comprises less than20 ppm of the fluorinated alkene of formula I, in certain preferredembodiments less than 200 ppm of the fluorinated alkene of formula I,and in further preferred embodiments less than 2,000 ppm of thefluorinated alkene of formula I. The resulting product stream may bestored or otherwise processed. In certain preferred embodiments, it isdehydrohalogenated to produce a second fluorinated olefin of formula I,wherein, in certain aspects, the second fluorinated olefin of formula Ihas one less fluorine atom than the starting fluorinated olefin.

In certain non-limiting aspects, one or both of the hydrogenationreaction above, or otherwise herein, are conducted, at least in part, ina liquid phase. Such reaction may also be conducted in the present of acatalyst, which may be selected from the group consisting of Pd oncarbon, Pd/α-Al₂O₃, Ni/C, and Ni/Al₂O₃.

In additional embodiments, the present invention relates to methods forproducing a fluorinated alkane by providing a starting material streamcomprising hexafluoropropene and 1,1,1,2,3,3-hexafluoropropane. Incertain non-limiting aspects, the ratio of hexafluoropropene and1,1,1,2,3,3-hexafluoropropane in the starting material stream is fromabout 1:3 to about 1:25, in certain preferred embodiments the ratio isfrom about 1:6 to about 1:22, and in further preferred embodiments theratio is from about 1:8 to about 1:20.

The starting material is then hydrogenated with a reducing agent (e.g.H₂) such that at least a portion of said hexafluoropropene is convertedto 1,1,1,2,3,3-hexafluoropropane and to produce an intermediate streamcomprising hexafluoropropene and 1,1,1,2,3,3-hexafluoropropane. Incertain non-limiting aspects, the hydrogenation step results in apercent conversion of the hexafluoropropene of between about 25 wt. %and about 75 wt. %, in certain preferred embodiments between about 35wt. % and about 65 wt. %, in further preferred embodiments between about40 wt. % and about 60 wt. %, and in even further preferred embodimentsbetween about 45 wt. % and about 55 wt. %.

The intermediate product stream is then separated into a firstintermediate product stream comprising hexafluoropropene and1,1,1,2,3,3-hexafluoropropane and a second intermediate product streamcomprising hexafluoropropene and 1,1,1,2,3,3-hexafluoropropane. To thefirst intermediate product stream additional hexafluoropropene may beadded, such that the ratio of the hexafluoropropene to thehexafluoropropene is from about 1:3 to about 1:25, in further aspectsfrom about 1:6 to about 1:22, and in even further aspects from about 1:8to about 1:20. The first intermediate is then recycled to thehydrogenation reactor.

The second intermediate stream is then hydrogenated in a secondhydrogenation reactor to produce a final product stream. In certainnon-limiting embodiments, the final product stream comprises less than20 ppm of hexafluoropropene, in certain preferred embodiments less than200 ppm of hexafluoropropene, and in further preferred embodiments lessthan 2,000 ppm of hexafluoropropene. This product stream may be stored,or in certain embodiments, dehydrohalogenated to form1,2,3,3,3-pentafluoropropene.

In further aspects, the present invention relates to methods forproducing a fluorinated alkane by providing a starting material streamcomprising 1,2,3,3,3-pentafluoropropene and1,1,1,2,3-pentafluoropropane. In certain non-limiting aspects, the ratioof 1,2,3,3,3-pentafluoropropene and 1,1,1,2,3-pentafluoropropane in thestarting material stream is from about 1:3 to about 1:25, in certainpreferred embodiments the ratio is from about 1:6 to about 1:22, and infurther preferred embodiments the ratio is from about 1:8 to about 1:20.

The starting material is then hydrogenated with a reducing agent (e.g.H₂) such that at least a portion of said 1,2,3,3,3-pentafluoropropene isconverted to 1,1,1,2,3-pentafluoropropane and to produce an intermediatestream comprising 1,2,3,3,3-pentafluoropropene and1,1,1,2,3-pentafluoropropane. In certain non-limiting aspects, thehydrogenation step results in a percent conversion of the1,2,3,3,3-pentafluoropropene of between about 25 wt. % and about 75 wt.%, in certain preferred embodiments between about 35 wt. % and about 65wt. %, in further preferred embodiments between about 40 wt. % and about60 wt. %, and in even further preferred embodiments between about 45 wt.% and about 55 wt. %.

The intermediate product stream is then separated into a firstintermediate product stream comprising 1,2,3,3,3-pentafluoropropene and1,1,1,2,3-pentafluoropropane and a second intermediate product streamcomprising 1,2,3,3,3-pentafluoropropene and1,1,1,2,3-pentafluoropropane. To the first intermediate product streamadditional 1,2,3,3,3-pentafluoropropene may be added, such that theratio of the 1,2,3,3,3-pentafluoropropene to the1,1,1,2,3-pentafluoropropane is from about 1:3 to about 1:25, in furtheraspects from about 1:6 to about 1:22, and in even further aspects fromabout 1:8 to about 1:20. The first intermediate is then recycled to thehydrogenation reactor.

In certain non-limiting embodiments, the final product stream comprisesless than 20 ppm of 1,2,3,3,3-pentafluoropropene, in certain preferredembodiments less than 200 ppm of 1,2,3,3,3-pentafluoropropene, and infurther preferred embodiments less than 2,000 ppm of1,2,3,3,3-pentafluoropropene. This product stream may be stored, or incertain embodiments, dehydrohalogenated to form2,3,3,3-tetrafluoropropene

Additional embodiments and advantages of the instant invention will bereadily apparent to one of skill in the art based on the disclosureprovided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process flow diagram showing the conversion of afluoroolefin to a fluoroalkene according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Traditional processes for the production of fluorocarbons that utilizehydrogenation technology, such as in the manufacture of HFC-134a,utilize large vapor recycle streams or a large shell and tube typereactor to handle the thermal management issues of the hydrogenationstep. Application of these types of technologies may be uneconomical dueto large equipment sizes and difficulties in process control. Theprocess of the present invention, at least in part, utilizes reactionsthat take place primarily in the liquid phase resulting in smaller andmore economical large-scale equipment, more robust process control, nearcomplete utilization of hydrogen, and an overall safer process thanpreviously described processes.

To this end, and in certain aspects, the present invention relates, atleast in part, to methods of increasing the cost efficiency and safetyfor hydrogenation of a fluorinated olefin, preferably in a commercial orlarge-scale manufacturing setting, by controlling the reactionconditions and parameters. As used herein, the term “reactionconditions” or “reaction parameters” is intended to include the singularand means control of any one or more processing parameters, includingpossibly using or not using a reaction vessel or stage, which can bemodified by the operator of the reaction to produce the conversionand/or selectivity of the feed material in accordance with the teachingscontained herein. By way of example, but not by way of limitation,conversion of the feed material may be controlled or regulated bycontrolling or regulating any one or more of the following: thetemperature of the reaction, the flow rate of the reactants, thepresence of diluent, the amount of catalyst present in the reactionvessel, the shape and size of the reaction vessel, the pressure of thereaction, and any one combinations of these and other process parameterswhich will be available and known to those skilled in the art in view ofthe disclosure contained herein.

In one aspect, the present invention relates to hydrogenation of afluorinated olefin (e.g. a pentafluoropropene and/or hexafluoropropene)to form a fluorinated alkane (e.g. pentafluoropropane and/orhexafluoropropane), wherein the amount of the starting fluorinatedolefin is diluted prior to hydrogenation with a fluorinated alkane, inpreferred aspects it is diluted with at least the targeted fluorinatedalkane product of the hydrogenation reaction. The reaction conditionsmay be controlled so as to produce a product stream wherein only aportion of the starting olefin was converted. From this product stream,a first portion, containing both the fluorinated olefin startingreactant and the fluorinated alkane product, is isolated and recycledback to the reactor. To this first portion, additional fluorinatedolefin starting material may be added before it is recycled to thehydrogenation reactor. The remaining portion of the product stream,which is also comprised of fluorinated olefin and fluorinated alkane, isthen provided to a second reactor for continued hydrogenation. The rateof hydrogen flow is controlled in this second reaction so as to controlthe fluorinated olefin conversion, temperature and pressure of thereaction. The final product produced from the second reaction may thenbe used or otherwise further processed, as required. In certainpreferred embodiments, it is then dehydrohalogenated to produce thedesired fluorinated olefin product or an intermediate product that maybe further processed.

In certain embodiments, the fluorinated olefins of the present inventioninclude one or more C3 to C6 fluoroalkenes, preferably compounds havinga formula as follows:X¹CF_(z)R_(3−z)where X¹ is a C2, C3, C4, or C5 unsaturated, substituted orunsubstituted, alkyl radical, each R is independently Cl, F, Br, I or H,and z is 1 to 3. Highly preferred among such compounds are propenes andbutenes having from 3 to 5 fluorine substituents, and among thesetetrafluoropropenes (HFO-1234) and pentafluoropropenes (HFO-1225) areespecially preferred.

In one embodiment, the process for producing the fluorinated olefins ofthe present invention include reacting a fluorinated olefin startingmaterial with a degree of halogen substitution of N+1 havingsubstantially the same number of carbon atoms as the fluorinatedolefin(s) to be synthesized with a degree of halogen substitution of N.The fluorinated olefin starting material preferably, though notexclusively, has a degree of fluorine substitution of N+1 and is exposedto reaction conditions effective to produce a reaction productcontaining one or more fluorinated alkanes having the same number ofcarbons atoms as the final olefin. This olefin conversion step includesa reaction that is sometimes referred to herein for convenience, but notnecessarily by way of limitation, as a reduction or hydrogenation step.The resulting fluorinated alkane is then converted to a fluorinatedolefin having a degree of fluorine substitution of N. This alkaneconversion step comprises a reaction that is sometimes referred toherein for convenience, but not necessarily by way of limitation, as adehydrohalogenation reaction or more particularly in certain embodimentsas a dehydrofluorination or dehydrochlorination reaction.

Based on the foregoing, in one aspect of the present invention, theprocess for producing a fluoroolefin includes the following steps:

(a) hydrogenating a compound of formula (I):(CX_(n)Y_(3−n))(CR¹ _(a)R² _(b))_(z)CX═CH_(m)X_(2−m)  (I)under conditions effective to form at least one fluorinated alkane offormula (II)(CX_(n)Y_(3−n))(CR¹ _(a)R² _(b))_(z)CHXCH_(m+1)X_(2−m)  (II)where:

each X is independently Cl, F, I or Br, provided that at least two Xsare F;

each Y is independently H, Cl, F, I or Br;

each R¹ is independently H, Cl, F, I, Br or unsubstituted or halogensubstituted methyl or ethyl radical;

each R₂ is independently H, Cl, F, I, Br or unsubstituted or halogensubstituted methyl or ethyl radical;

n is 1, 2 or 3;

a and b are each 0, 1 or 2, provided that a+b=2;

m is 0, 1 or 2; and

z is 0, 1, 2 or 3; and

(b) dehydrohalogenating the compound of formula (II) under conditionseffective to produce a fluoroolefin with a lower degree of fluorinesubstitution than the compound of formula (I), preferably to produce acompound of formula (III):(CX_(n)Y_(3−n))(CR¹ _(a)R² _(b))_(Z)CX═CH_(m+1)X_(1−m)  (III)where each n is the same value as in formula (I) and m is 0 or 1.

In further non-limiting embodiments, the reactant of formula (I) mayinclude a three carbon olefin of formula (IA) wherein z is 0, namelyCX_(n)Y_(3−n)CX═CH_(m)X_(2−m)  (IA)to produce a three carbon alkane of formula (IIA) as follows:(CX_(n)Y_(3−n))CHXCH_(m+1)X_(2−m)  (IIA)where X, Y, n, and m are all as indicated above, which compound is thendehydrohalogenated to form a compound of formula (IIIA)(CX_(n)Y_(3−n))CX═CH_(m+1)X_(1−m)  (IIIA)where n is the same value as in formula (IA) and m is 0 or 1.

In even further embodiments, the instant invention provides a saturatedterminal carbon of the compounds of formulas (I) or (IA) that is fullysubstituted with fluorine (for example, n on the saturated terminalcarbon is 3 and each X on that carbon is F). In such embodiments, thecompound of Formula (I) or (IA) is preferably a fluoropropene havingfrom three to six fluorine substituents, and potentially other halogensubstituents, including for example hexafluoropropene (that is, Z is 0,n is 3, m is 0, and all X are F) or pentafluoropropene (that is, Z is 0,n is 3, m is 1, and all X are F). The resulting compound of formula (II)or (IIA) is selected from the group consisting of, one or more of thefollowing fluorinated alkanes: pentafluoropropane (HFC-245) andhexafluoropropane (HFC-236), including all isomers of each of these, butpreferably 1,1,1,2,3-pentafluoropropane (HFC-245eb),1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and combinations of these. Incertain preferred embodiments the fluorinated alkane produced by theconversion step has a degree of fluorine substitution of N+1.

In any of the foregoing reactions, the step wherein the olefin isconverted to an alkane is carried out under conditions effective toprovide a formula (I) conversion of at least about 40%, more preferablyat least about 55%, and even more preferably at least about 70%. Incertain preferred embodiments the conversion is at least about 90%, andmore preferably about 99%. Further in certain preferred embodiments, theconversion of the compound of formula (I) or (IA) to produce a compoundof formula (II) is conducted under conditions effective to provide aformula (II) or (IIA) selectivity of at least about 60%, more preferablyat least about 80%, and more preferably at least about 90%, and evenmore preferably about 100%.

In any of the foregoing reactions, the step wherein the alkane isconverted to a fluorinated olefin having a degree of fluorination of Nis carried out under conditions effective to provide a formula (II)conversion of at least about 40%, more preferably at least about 55%,and even more preferably at least about 70%. In certain preferredembodiments the conversion is at least about 90%, and more preferablyabout 95%. Further in certain preferred embodiments, the conversion ofthe compound of formula (II) to produce a compound of formula (III) isconducted under conditions effective to provide a formula (III)selectivity of at least about 60%, more preferably at least about 80%,and more preferably at least about 90%, and even more preferably about98%.

The Hydrogenation Step

Although it is contemplated that the hydrogenation or reduction step maybe conducted in batch operation, it is preferred that the hydrogenationreaction is carried out as a substantially continuous operation. Whileit is further contemplated that the hydrogenation reaction may beconducted in a single reaction vessel, in certain preferred embodimentsthis reaction step may comprise two or more reactors or reaction stagesin parallel, in series, or both, or any combination of reactor designs.In addition, it is contemplated that the reaction step may include oneor more feed preheating or precooling steps or stages, depending on theparticulars of each application.

While it is possible that the reaction may involve in certainembodiments a liquid phase reaction, a vapor phase reaction orcombinations of both, it is contemplated that in certain embodiments thehydrogenation reaction comprises at least liquid phase reaction stage,and in certain preferred embodiments at least two stages of liquid phasereactions.

In certain non-limiting embodiments, and referring to FIG. 1, thehydrogenation reaction is provided within a system 1 that includes atleast a first hydrogenation reactor 10 and a second hydrogenationreactor 20 for the hydrogenation of the fluorinated olefin to form thefluorinated alkane. The starting feed stream 5 is provided to the firstreactor 10 from a starting source, such as a feed drum 15. Prior toentering the first reactor 10, the starting feed stream of fluorinatedolefin is diluted with a fluorinated alkane product. In certainpreferred embodiments, such an alkane comprises, consists essentiallyof, or consists of the targeted fluorinated alkane produced by thehydrogenation of the starting fluorinated olefin.

In certain aspects, such as at the initiation of the reaction, thestarting feed stream may be provided with fluorinated olefin that hasalready been diluted with the fluorinated alkane. In further aspects,however, the fluorinated olefin is provided from the source (e.g. feeddrum) in a substantially pure form and is diluted with product streamrecycled from the first reactor 10, such as that depicted at referencenumber 25 of FIG. 1 and discussed in greater detail below. By way ofnon-limiting example, in an embodiment where the starting feed streamincludes hexafluoropropene, the feed stream is diluted with at least1,1,1,2,3,3-hexafluoropropane (HFC-236ea). In embodiments where thestarting feed stream is 1,2,3,3,3-pentafluoropropene (HFO-1225ye), it isdiluted with at least 1,1,1,2,3-pentafluoropropane (HFC-245eb).

The ratio of fluorinated olefin to fluorinated alkane in the dilutedfeed stream may be any amount that is effective to control one or moreparameters of the reaction, such as, but not limited to, the temperatureinside the reactor, the selectivity of the product produced, theconversion percentage or conversion rate of the product, or the like.Preferably, the hydrogenation reaction conditions are controlled in thereaction in order to achieve the desired conversion percentage of thefluorinated olefin and/or selectivity of the targeted fluorinated alkanein accordance with the present invention. In certain non-limitingembodiments, the ratio of fluorinated olefin to fluorinated alkane inthe feed stream provided to the first reactor ranges from about 1:3 toabout 1:25, in certain preferred embodiments from about 1:6 to about1:22; in further preferred embodiments from about 1:8 to about 1:20. Itis to be understood, however, that such ratio are not necessarilylimiting and may be adjusted, based on the reaction performed and thedesired outcome (e.g. conversion percentage, selectivity percentages,maximizing dissolution of hydrogen in the reaction mass [i.e. if H₂ isnot too soluble, the fluorinated alkane is increased so as to increasethe amount in which the H₂ will dissolve] and the like).

Prior to entering the first reactor, the diluted fluorinated olefin feedstream is mixed with a hydrogen feed stream 35. The amount of hydrogenprovided may be any amount that is effective to control one or more ofthe temperature of the reaction, the temperature inside the reactor, theselectivity of the product produced, the conversion percentage orconversion rate of the product, or the like. In certain non-limitingembodiments, the hydrogen feed is provided in excess of the amount ofstarting fluorinated olefin. That is, in certain aspects, the ratio ofhydrogen to fluorinated olefin is greater than 1:1. The fluorinatedolefin feed and hydrogen may be mixed before the reaction using standardmeans, such as, but not limited to, a static mixer 36. In otherembodiments, the ratio of hydrogen to fluorinated olefin is less than1:1. It is to be understood, however, that such ratio are notnecessarily limiting and may be adjusted, based on the reactionperformed and the desired outcome (e.g. temperature control, conversionpercentage, selectivity percentages, condition of the feed to secondreactor, and the like).

Also prior to entering the first reactor, the temperature of the dilutedolefin/hydrogen feed stream may be optionally controlled by passing itthrough a cooling element 30. Such cooling element is used to cool thetemperature of the reactants into the first reactor as the temperatureof recycle stream 50 is hotter than the desired first reactor inlettemperature due to the exothermic nature of the hydrogenation reaction.Since the reduction or hydrogenation reaction of the present inventionis generally exothermic, and usually substantially exothermic, the useof such cooled material has the effect in preferred embodiments ofmaintaining the reactor temperature below that which would exist if therecycle were not used, assuming all other process conditions weremaintained the same.

As illustrated in FIG. 1, however, the present invention is not limitedto the inclusion of a precooling step and may also include a by-pass 40of the cooling element directly to the reactor 10, particularly if thefeed stream is at a desired temperature or within a desired temperaturerange.

The hydrogenation reaction can be catalyzed using any hydrogenationcatalyst, and in certain embodiments a liquid phase hydrogenationcatalyst. According to certain preferred embodiments of the invention,carbon or alpha-alumina supported metal catalysts are employed in thehydrogenation of fluoroolefins to hydrofluorocarbons. Non-limitingexamples of metal components include Pd, Ru, Pt, Rh, Ir, Fe, Co, Ni, Cu,Ag, Re, Os, Au, and any combinations thereof. The metal loading can varywithin a large range, e.g., from 0.1-10 wt %. However, for noble metalssuch as Ru, Ph, Pd, Pt, Ir, etc., the metal loading is preferably about0.1 to about 5 wt %, and more preferably about 0.1 to about 1 wt %. Ithas been discovered that supported catalyst having metal concentrationsbelow about 0.1 wt. % are not highly effective at hydrogenatingfluoroolefins or hydrofluoroolefins. Preferably, though not exclusively,the hydrogenation catalyst is selected from the group consisting of Pdon carbon, Pd/α-Al₂O₃, Ni/C, and Ni/Al₂O₃

While it is contemplated that a wide variety of hydrogenation reactiontemperatures may be used, depending on relevant factors such as thecatalyst being used and the most desired reaction product, it isgenerally preferred that such conditions be controlled so as to providethe reaction in a liquid phase. To this end, and in certain non-limitingaspects, the reaction temperature for the hydrogenation step is fromabout 10° C. to about 500° C., preferably about from 25° C. to about400° C., and even more preferably from about 50° C. to about 300° C.

It is further contemplated that a wide variety of reaction pressures maybe used. In the aspects of the invention, however, the pressure withinthe first reactor may be such that hydrogenation reaction is conductedsubstantially in the liquid phase. Such pressures may include, forexample, from about 100 psig to about 1,500 psig and in certainpreferred embodiments from about from 200 psig to about 1,000 psig.

Again, in certain preferred aspects, the hydrogenation of thefluorinated olefin in the first reactor is limited so as to control theexothermic nature of the reaction, and thereby the temperature withinthe reactor. Hydrogenation reactions, by nature, are highly exothermic.This is particularly true with the conversion of HFP to HFC-236ea andHFO-1225ye to HFC-245eb, as illustrated by the negative enthalpy valuesbelow.

Accordingly, and in addition to one or more of the parameters above, thetemperature within the reactor is also controlled by limiting thecontact time of the fluorinated olefin, H₂ and the catalyst. Suchcontact times may include but are not limited to from about 1 to about180 seconds preferably from about 5 to about 60 seconds. The presentinvention is not limited the foregoing, and such times may also includeany amount to keep the reactor within commercially tolerable temperaturelevels.

In certain non-limiting embodiments, however, the contact times,temperature, pressure, reactant flow/concentration, etc. are controlledto result in a percent conversion of the fluorinated olefin is betweenabout 25 wt. % and about 75 wt. %; in certain preferred embodimentsbetween about 35 wt. % and about 65 wt. %; in further preferredembodiments between about 40 wt. % and 60 wt. %; in even furtherpreferred embodiments between about 45 wt. % and about 55 wt. % and ineven further preferred embodiments about 50 wt. %.

The product stream emerging from the reactor 10 is then divided where afirst portion 45 of it is provided to a second reactor for furtherprocessing and the remaining (or second) portion is recycled 50. Theflow of the latter, recycled portion is controlled to contain aneffective amount of fluorinated olefin and fluorinated alkane product,such that when it is combined with the pure fluorinated olefin feedstream at point 25, the resulting level of the diluted fluorinatedolefin will be in accordance with that above. To this end, and incertain preferred embodiments, the level of fluorinated olefin in therecycled portion is such that, when it is combined with additionalfluorinated olefin, the resulting ratio of fluorinated olefin tofluorinated alkane in the feed stream provided to the first reactor mayranges from about 1:3 to about 1:25, in certain preferred embodimentsfrom about 1:6 to about 1:22; in further preferred embodiments fromabout 1:8 to about 1:20.

While a myriad of other factors also may be used to determine how muchof the product stream is recycled 45 and how much is fed to the secondreactor for further hydrogenation, in certain aspects, the amount ofrecycle is determined by the degree of exotherm (i.e. the temperature ofthe product stream) that can be tolerated by the system. In certainnon-limiting aspects, it is desirable to maintain the temperature of theproduct stream to less than about 200° C., in certain preferred aspectsto less than about 100° C., in further aspects to less than about 50°C., and in even further aspects to less than about 35° C. To this end,the amount of product stream that is recycle is such that the resultingproduct of the recycle can be maintained to within these temperatures.

The portion of the feed stream that is not recycled 45, is then feed tothe second reactor 20 for further hydrogenation and to react theremaining fluoroolefin down to very low concentration levels. In certainnon-limiting embodiments, the ratio of fluorinated olefin to fluorinatedalkane in the feed stream provided to the second reactor ranges fromabout 1:3 to about 1:25, in certain preferred embodiments from about 1:6to about 1:22; in further preferred embodiments from about 1:8 to about1:20. It is to be understood, however, that such ratio are notnecessarily limiting and may be adjusted, based on the reactionperformed and the desired outcome (e.g. conversion percentage,selectivity percentages, and the like).

Prior to entering the second reactor 20, the diluted fluorolefin feedstream 45 is provided with hydrogen feed stream 55, and may be mixedusing standard means, such as, but not limited to, a static mixer 66.The amount of hydrogen may be any amount to control the temperature ofthe reaction, desired rate of conversion, or the like. To this end, andin certain preferred embodiments, the feed rate of hydrogen,amount/dilution of the fluorinated olefin, reaction parameters, and thelike is controlled to result in a conversion rate that is greater than,and preferably substantially greater than, the conversion rate in thefirst reaction stage. In certain preferred embodiments, for example, theconversion percentage in the second reaction stage is from about 20% toabout 99%. In further preferred embodiments, the conversion in thesecond reaction stage is preferably greater than 95%, and even morepreferably about 100%. To this end, and in certain preferredembodiments, the product stream exiting the second reactor may have alevel of unreacted fluorinated olefin of less than 20 ppm, preferablyless than 200 ppm, and most preferably to less than 2,000 ppm.

Also prior to entering the second reactor, the temperature of thediluted olefin/hydrogen feed stream may be optionally controlled bypassing it through a cooling element 65. Such cooling element is used tocontrol the temperature of the reactants into the second reactor as feedstream 45, which came directly out of the 1^(st) reactor, is hotter thanthe desired second reactor inlet temperature due to the exothermicnature of the hydrogenation reaction. Since the reduction orhydrogenation reaction of the present invention is generally exothermic,and usually substantially exothermic, the use of such cooled materialhas the effect in preferred embodiments of maintaining the reactortemperature below that which would exist if the cooling element were notused, assuming all other process conditions were maintained the same.

As illustrated in FIG. 1, the present invention is not limited to suchan aspect and may also include a by-pass 70 to the cooling elementdirectly to the reactor 20, particularly if the feed stream is at adesired temperature or within a desired temperature range.

The hydrogenation reaction in the second reactor can be catalyzed usingany hydrogenation catalyst. According to a preferred embodiment of theinvention, carbon or alpha-alumina supported metal catalysts areemployed in the hydrogenation of fluoroolefins to hydrofluorocarbons.Non-limiting examples of metal components include Pd, Ru, Pt, Rh, Ir,Fe, Co, Ni, Cu, Ag, Re, Os, Au, and any combinations thereof. The metalloading can vary within a large range, e.g., from 0.1-10 wt %. However,for noble metals such as Ru, Ph, Pd, Pt, Ir, etc., the metal loading ispreferably about 0.1 to about 5 wt %, and more preferably about 0.1 toabout 1 wt %. It has been discovered that supported catalyst havingmetal concentrations below about 0.1 wt. % are not highly effective athydrogenating fluoroolefins or hydrofluoroolefins. Preferably, thoughnot exclusively, the hydrogenation catalyst is selected from the groupconsisting of Pd on carbon, Pd/α-Al₂O₃, Ni/C, and Ni/Al₂O₃.

While it is contemplated that a wide variety of hydrogenation reactiontemperatures may be used, depending on relevant factors such as thereactant fluoroolefin, heat of reaction, catalyst being used and themost desired reaction product, it is generally preferred that suchconditions be controlled so as to provide the reaction in a liquidphase. To this end, and in certain non-limiting aspects, the reactiontemperature for the hydrogenation step is from about 10° C. to about500° C., preferably about from 25° C. to about 400° C., and even morepreferably from about 50° C. to about 300° C.

It is further contemplated that a wide variety of reaction pressures maybe used, again, in the aspects of the invention the pressure within thefirst reactor may be such that hydrogenation reaction is conducted inthe liquid phase. The reaction pressure can be, for example, from about100 psig to about 1,500 psig and in certain preferred embodiments fromabout from 200 psig to about 1,000 psig.

The product steam exiting the second reactor 20, can then be optionallycooled by a cooling element 80. In certain aspects, it may be optionallycooled to any final temperature that is desirable for additionalprocessing, end processing, storage, or any other use for the productsproduced during the reaction. In certain preferred aspects, the productstream is cooled to a temperature from about 20° C. to about 100° C.,more preferably from about 20° C. to about 90° C., and most preferablyfrom about 20° C. to about 70° C., which is optimal fordehydrohalogenation (discussed below).

The size and shape, and other characteristics of the reaction vessels(e.g. first and second reactors) may vary widely with the scope of thepresent invention, and it is contemplated that the vessel associatedwith each stage may be different than or the same as the vesselassociated with the upstream and downstream reaction stages.Furthermore, it is contemplated that all reaction stages can occurinside a single vessel, provided that means and mechanisms necessary tocontrol conversion are provided in accordance with the above. Forexample, it may be desirable in certain embodiments to utilize a singletubular reactor for each reaction stage, providing conversion control byjudicious selection of the amount and/or distribution of catalystthroughout the tubular reactor. In such a case, it is possible tofurther control the conversion in different sections of the same tubularreactor by controlling the amount of heat removed from or added todifferent sections of the tubular reactor. Means to remove heat areknown in the art and include interstage cooling of a portion of the flowand returning to the main flow; cold shot liquid wherein an amount ofreaction product is injected into the intermediate stream.

Dehydrohalogenation

In certain non-limiting aspects of the invention, the final fluorinatedalkane product stream exiting the second reactor is dehydrohalogenatedto produce a fluorinated olefin having one less fluorine atom that thestarting olefin. This dehydrofluorination step can be carried out in aliquid phase in the presence of a dehydrohalogenation agent (e.g.caustic solution) or a gas phase in the presence of adehydrofluorination catalyst. It is contemplated that the reaction maybe carried out batchwise, continuously or a combination thereof.

In one embodiment the converting step involves a reaction in which thefluorinated alkane (e.g. HFC-245eb and/or HFC-236ea) is contacted with adehydrohalogenating agent such as KOH, NaOH, Ca(OH)₂, LiOH, Mg(OH)₂,CaO, and combinations thereof to form the fluorinated olefin. By way ofexample, if KOH is used, such a reaction may be described by way ofillustration, but not necessarily by way of limitation, by the followingreaction equations (1) and (2):CF₃—CHF—CHF₂+KOH→CF₃CF═CHF+KF+H₂O  (1)CF₃—CHF—CH₂F+KOH→CF₃CF═CH₂+KF+H₂O  (2)

The dehydrohalogenating agent may be provided as a caustic aqueoussolution comprising from about 2% to about 100%, more preferably fromabout 10% to about 50%, and even more preferably from about 10% to about50% by weight of dehydrohalogenating agent. In further embodiments, thecaustic solution, and preferably the dehydrohalogenating agent solution,is brought to a temperature of from about 20° C. to about 100° C., morepreferably from about 20° C. to about 90° C., and most preferably fromabout 20° C. to about 70° C. The reaction pressure in such embodimentsmay vary, depending on particular processing parameters of eachapplication. In certain embodiments, the reaction pressure ranges fromatmospheric pressure, super-atmospheric pressure or under vacuum. Thevacuum pressure, when used, in certain embodiments ranges from about 5torr to about 760 torr.

It is contemplated that the amount of dehydrohalogenation agent (orreagent) used, or mole ratio of reagent to organic, will vary dependingon the particular parameters present in each embodiment. In certainembodiments, the mol ratio of dehydrohalogenating agent to fluorinatedalkane is from less than 1 to 3, preferably 1-1.5. In furtherembodiments, the contact time, which is expressed as the ratio of thevolume of the reagent (ml) to the total feed flow (ml/sec) is from about0.1 seconds to about 1000 seconds, and preferably from about 2 secondsto about 120 seconds.

The dehydrohalogenation reactions can be accomplished using any suitablevessel or reactor. Such vessels or reactors should be constructed frommaterials which are resistant to corrosion, such as stainless steel,nickel and its alloys, including Hastelloy, Inconel, Incoloy, and Monel.In certain embodiments, this reaction is performed using one or a seriesof Continuously Stirred Tank Reactors (CSTR). In this type of reactor,fluorinated alkane feed and dehydrohalogenating agent would be fedcontinuously into the reactor and the resulting product stream formedwould be fed into a condenser or distillation column for separation offluorinated olefin product (e.g. 1225ye and/or 1234yf) from andun-reacted fluorinated alkane, as well as other by-products of thereaction.

In certain embodiments, spent dehydrohalogenating agent is removed fromthe product stream either periodically or continuously and is recycledback to the reactor for reuse. As noted previously, Applicants havediscovered that, during continuous processing the reaction proceedsuntil either the fluorinated alkane reactants or dehydrohalogenatingagent is consumed. This increases costs of productivity because thereactor must be dismantled upon completion of the reaction to remove thesalt and/or salt solutions. By recycling the dehydrohalogenating agentand by-product salts, however, such costs may be reduced and the systemmade more efficient.

Spent dehydrohalogenating agent and by-product salts (e.g. metalfluoride salts) may be withdrawn from the reactor by a product streameither continuously or intermittently using one or more known separationtechniques. To this end, spent dehydrohalogenating agent separation mayoccur using any known compound separation techniques, such, but notlimited to, distillation, phase separation, etc. In certain embodiments,withdrawal of spent dehydrohalogenating agent is especially beneficialfor component separation as it allows for facile separation of organicand dehydrohalogenating agent. This in turn leads to lower costassociated with design and operation of complicated and highlyspecialized separation equipment.

The product stream containing spent dehydrohalogenating agent typicallycarries with it some dissolved fluorinated alkane. By stopping thestirrer and then removing spent dehydrohalogenating agent during thetime agitation is stopped, separation of dehydrohalogenating agent andsuch alkane can be facilitated. Spent dehydrohalogenating agent anddissolved alkane would be taken into a container where additionalseparation of dehydrohalogenating agent and alkane can be accomplishedusing one or more of the foregoing separation techniques. In onenon-limiting embodiment, for example, KOH is separation by distillation,i.e. by heating the alkane just above its boiling point, thusfractionating it from the spent KOH. Alternatively, one can use phaseseparator to separate between the two phases. The organic free KOHisolate can be immediately recycled to the reactor or can beconcentrated and the concentrated solution can be returned to reactor.

The by-product salt can also be isolated and converted back to thedehydrohalogenating agent used known methods. When KOH is used as thedehydrohalogenating agent, for example, KF is formed as a by-productsalt. Such salt may be converted back to KOH and recycled back to thedehydrohalogenation reaction. For example, Ca(OH)₂ can be used for KFconversion according to reaction below.2KF+Ca(OH)₂→2KOH+CaF₂CaF₂ will precipitate from the foregoing reaction while KOH is isolatedand recycled back to reactor. Recycling of spent dehydrohalogenatingagent leads to better efficiency of the reagent use. Moreover, the useof recycling of the by-product salt reduces dehydrohalogenating agentuse, reduces costs of reagents and costs associated with disposal of thesalt, and/or purchase of new raw material.

In another embodiment the dehydrohalogenation step involves a reactionin which the fluorinated alkane (e.g. HFC-245eb and/or HFC-236ea) iscontacted with a dehydrohalogenating catalyst in the vapor phase. Theprocess involves the catalytic conversion of HFC-245eb and/or HFC-236eaby dehydrofluorinating HFC-245eb or HFC-236ea to form the fluorinatedolefin. By way of example, if a vapor phase catalyst is used, such areaction may be described by way of illustration, but not necessarily byway of limitation, by the following reaction equations (1) and (2):

Vapor phase dehydrofluorination reactions are well known in the art.Preferably dehydrofluorination of HFC-245eb and HFC-236ea is done in avapor phase, and more preferably in a fixed-bed reactor in the vaporphase. The dehydrofluorination reaction may be conducted in any suitablereaction vessel or reactor, but it should preferably be constructed frommaterials which are resistant to the corrosive effects of hydrogenfluoride such as nickel and its alloys, including Hastelloy, Inconel,Incoloy, and Monel or vessels lined with fluoropolymers. These may besingle or multiple tubes packed with a dehydrofluorinating catalystwhich may be one or more of fluorinated metal oxides in bulk form orsupported, metal halides in bulk form or supported, and carbon supportedtransition metals, metal oxides and halides. Suitable catalystsnon-exclusively include fluorinated chromia (fluorinated Cr₂O₃),fluorinated alumina (fluorinated Al₂O₃), metal fluorides (e.g., CrF₃,AlF₃) and carbon supported transition metals (zero oxidation state) suchas Fe/C, Co/C, Ni/C, Pd/C or transition metals halides. The HFC-245eb orHFC-236ea is introduced into the reactor either in pure form, impureform, or together with an optional inert gas diluent such as nitrogen,argon, or the like. In a preferred embodiment of the invention, theHFC-245eb or HFC-236ea is pre-vaporized or preheated prior to enteringthe reactor. Alternately, the HFC-245eb or HFC-236ea is vaporized insidethe reactor. Useful reaction temperatures may range from about 100° C.to about 600° C. Preferred temperatures may range from about 150° C. toabout 450° C., and more preferred temperatures may range from about 200°C. to about 350° C. The reaction may be conducted at atmosphericpressure, super-atmospheric pressure or under vacuum. The vacuumpressure can be from about 5 torr to about 760 torr. Contact time of theHFC-245eb or HFC-236ea with the catalyst may range from about 0.5seconds to about 120 seconds, however, longer or shorter times can beused.

The resulting products may be isolated from the product stream using oneor more methods known in the art and purified accordingly.

In certain non-limiting aspects of the foregoing hydrogenation anddehydrohalogenation reactions, the starting reagents hexafluoropropene(HFP) and/or HFO-1225ye are hydrogenated to produce the fluorinatedalkanes HFC-236ea and HFC-245eb, respectively. That is HFP and/orHFO-122ye are hydrogenated in accordance with two stage reaction methodsprovided herein to produce a reaction produced comprising HFC-236eaand/or HFC-245eb. HFC-236ea is then dehydrohalogenated to produceHFO-1225ye, and HFC-245eb is dehydrohalogenated to produce HFO-1234yf.

In even further embodiments the hydrogenation and dehydrohalogenationsteps may be performed in series to convert HFP into HFO-1234yf. Thatis, HFP is hydrogenated in accordance with the two stage reactionmethods provided herein to produce the fluorinated alkane HFC-236eaHFC-236ea is then dehydrohalogenated to produce HFO-1225ye, which isthen isolated and halogenated, in accordance with the two stage reactionmethods discussed herein, to produce HFC-245eb. This alkane is thendehydrohalogenated in accordance with the methods provided herein toproduce HFO-1234yf.

EXAMPLES

The following examples are provided for the purpose of illustrating thepresent invention but without limiting the scope thereof.

Examples 1-3—Hexafluoropropene—1^(st) Stage Reaction Studies

A reactor was constructed of 2 parallel lengths of ½″ SS tubing. Thefirst length was the preheater and was heated by electrical heat tapeand insulated. It was packed with nickel mesh to facilitate heattransfer and mixing. The second length had a ⅛″ profile probe insertedinside it from top to bottom to monitor the catalyst bed temperature.The reactor was loaded with about 21 grams (50 cc) of Aldrich 1% Pd/Ccatalyst and had electrical heat tape and insulation around it forheating. The catalyst was treated prior to initial startup by flowing200 ml/min H₂ over the catalyst starting at room temperature and heatingup to a hot spot of 225° C. The temperature was held at 225° C. for 8hours.

Three experiments were run using a diluted hexafluoropropene (HFP) feedin the intended product hexafluoropropane with the goal of achievingabout 50% conversion of HFP while managing the heat of reaction. Theexperiments were run at about 290 psig and 200° C. Experiment 1 used afeed that had about 7.5 GC area % HFP. The average conversion for the 12hour experiment was 50.5% when using a 0.55:1 mole ratio of H₂ to HFP.The selectivity for desired products was 98.0%. Experiment 2 used a feedthat had about 12.7 GC area % HFP. The average conversion for the 10hour experiment was 50.2% when using a 0.55:1 mole ratio of H₂ to HFP.The selectivity for desired products was 98.6%. Experiment 3 used a feedthat had about 20.5 GC area % HFP. The average conversion for the 12hour experiment was 57.2% when using a 0.6:1 mole ratio of H₂ to HFP.The selectivity for desired products was 98.4%. Temperature controlwithin the reactor was not an issue when the goal of about 50% HFPconversion was achieved.

Experimental data can be found in Tables 1 and 2 below.

TABLE 1 GC area % of the various diluted HFP feed materials used forexperiments 1-3 Exp# HFP 1234yf 1225yez 236ea 254iso 245fa 245eb 1234zecis 254fb others 1 7.545 0.027 0.138 90.001 0.269 0.183 0.237 0.0871.342 0.171 2 12.742 0.037 0.227 84.956 0.264 0.17 0.262 0.005 1.1440.193 3 20.497 0.033 0.309 76.949 0.236 0.175 0.45 0 1.079 0.272

TABLE 2 Summary of HFP hydrogenation experiments 1-3 Average selec-Organic Average tivity of useful Pres- feed H2:HFP Temper- HFP products(1234yf, sure rate mole ature conver- 1225ye, 236ea, Exp# (Psig) (lb/hr)ratio (° C.) sion 245eb) 1 290 1.085 0.55 200 50.5 98.0 2 290 1.085 0.55200 50.2 98.6 3 290 1.085 0.6 200 57.2 98.4

Example 4—Hexafluoropropene—1^(st) Stage Reaction Studies

The reactor effluent stream from Example 1 is fed into a secondhydrogenation reactor along with a small stoichiometric excess amount ofH₂ compared to the total amount of olefins in the feed. The reactordesign is the same as used for Example 1-3. The reactor is loaded withabout 23 grams (50 cc) of Aldrich 1% Pd/C catalyst and has electricalheat tape and insulation around it for heating. The catalyst ispretreated in the same way as Example 1-3. The organic feed containsabout 3.25 GC area % HFP and is fed at a rate of 0.75 lb/hr. The reactoris run at a pressure of 200° C. and at a pressure of about 300 psig. Thereactor effluent is analyzed by GC and is found to contain only 0.05%HFP. The selectivity to the desired hexafluoropropane product is >98.5%.

Examples 5-7—1,2,3,3,3-pentafluoropropene—1^(st) Stage Reaction Studies

A reactor was constructed of 2 parallel lengths of ½″ SS tubing. Thefirst length was the preheater and was heated by electrical heat tapeand insulated. It was packed with nickel mesh to facilitate heattransfer and mixing. The 2^(nd) length had a ⅛″ profile probe insertedinside it from top to bottom to monitor the catalyst bed temperature.

50 cc (20.8 grams) of fresh Aldrich 1% Pd/C were charged to the ½″OD×30″ L tube reactor. The catalyst was treated prior to initial startupby flowing 200 ml/min H₂ over the catalyst starting at room temperatureand heating up to a hot spot of 225° C. The temperature was held at 225°C. for 8 hours.

Three experiments were run using a diluted 1,2,3,3,3-pentafluoropropene(1225ye) feed in the intended product 1,1,1,2,3-pentafluoropropane(245eb) with the goal of achieving about 50% conversion of 1225ye whilemanaging the heat of reaction. The feed for all three experimentscontained about 11.4% combined 1225ye Z and E isomers, but alsocontained about 2.5 GC area % of the unsaturated fluorinated olefin HFP.Experiment 1 was run at a temperature of 80° C. and at a pressure of 395psig. The average conversions for the 8 hour experiment were 39.9% for1225ye (combined Z and E isomer) and 99.7% for HFP when using a 0.55:1mole ratio of H₂ to 1225ye/HFP combined. This was a utilization of about96.7% of the H₂ fed. The selectivity for 245eb was 98.6%. Experiment 2was run at a temperature of 200° C. and at a pressure of 395 psig. Theaverage conversions for the 9 hour experiment were 36.2% for 1225ye(combined Z and E isomer) and 96.6% for HFP when using a 0.55:1 moleratio of H2 to 1225ye/HFP combined. This was a utilization of about90.6% of the H2 fed. The selectivity for 245eb was 98.9%. Experiment 3was run at a temperature of 100° C. and at a pressure of 395 psig. Theaverage conversions for the 9 hour experiment were 38.5% for 1225ye(combined Z and E isomer) and 99.1% for HFP when using a 0.55:1 moleratio of H2 to 1225ye/HFP combined. This was a utilization of about95.0% of the H₂ fed. The selectivity for 245eb was 99.4%. Temperaturecontrol within the reactor was not an issue when the goal of about 50%1225ye conversion was achieved. Experimental data can be found in Tables3 and 4 below.

TABLE 3 Feed Compositions for Exp# 1225ye-1, 1225ye-2, and 1225ye-3 GCArea % Exp 1234yf 1225yeZ 1225yee 254eb 236ea 245eb 254fb others1225ye-1-3 2.49 10.95 0.43 4.40 0.00 81.41 0.13 0.18

TABLE 4 Experimental Data Summary for Exp# 1225ye-1, 1225ye-2, 1225ye-3Overall 1225ye(Z) and 1234yf 254eb 245eb 245fb Others Cal. H2 1225ye(E)Conv. Sel. Sel. Sel. Sel. consumed Exp# Conditions Con. (molar %) mol %mol % mol % mol % mol. % (%) 1225ye-1 80 C., 395 psig, 39.9 99.7 0.898.6 0.6 0.0 96.7 0.55 H2/olefin 1225ye-2 200 C., 395 psig, 36.2 96.60.6 98.9 0.5 0.0 90.6 0.55 H2/olefin 1225ye-3 100 C., 395 psig, 38.599.1 0.0 99.4 0.6 0.0 95.0 0.55 H2/olefin

Example 8—1,2,3,3,3-pentafluoropropene—2^(nd) Stage Reaction Studies

The reactor effluent stream from Example 5 is fed into a 2^(nd)hydrogenation reactor along with a small stoichiometric excess amount ofH2 compared to the total amount of olefins in the feed. The reactordesign is the same as used for Example 5-7. The reactor is loaded withabout 23 grams (50 cc) of Aldrich 1% Pd/C catalyst and has electricalheat tape and insulation around it for heating. The catalyst ispretreated in the same way as Example 5-7. The organic feed containsabout 6.8 GC area % HFP and is fed at a rate of 0.55 lb/hr. The reactoris run at a pressure of 100° C. and at a pressure of about 400 psig. Thereactor effluent is analyzed by GC and is found to contain only 0.1%1225yeE and 1225yeZ. The selectivity to the desired1,1,1,2,3-pentafluoropropane (245eb) product is >98.0%.

What is claimed is:
 1. A method for producing at least one fluorinatedalkane comprising: a. providing a starting material stream comprising atleast one alkene according to Formula (I)(CX_(n)Y_(3−n))(CR¹ _(a)R² _(b))_(z)CX═CH_(m)X_(2−m)  (I) and at leastone alkane according to Formula (II)(CX_(n)Y_(3−n))(CR¹ _(a)R² _(b))_(z)CHXCH_(m+1)X_(2−m)  (II) wherein:each X is independently Cl, F, I or Br, provided that at least two Xsare F; each Y is independently H, Cl, F, I or Br; each R¹ isindependently H, Cl, F, I, Br or unsubstituted or halogen substitutedmethyl or ethyl radical; each R² is independently H, Cl, F, I, Br orunsubstituted or halogen substituted methyl or ethyl radical; n is 1, 2or 3; a and b are each 0, 1 or 2, provided that a+b=2; m is 0, 1 or 2;and z is 0, 1, 2 or 3, b. hydrogenating the starting material stream ina liquid phase reaction in a first reactor to produce an intermediatematerial stream by contacting said starting material stream with areducing agent such that at least a portion of the fluorinated alkene ofFormula I is converted to the fluorinated alkane of Formula II, whereinthe selectivity of the conversion to said fluorinated alkane of FormulaII is at least about 80 wt %; c. separating a portion of theintermediate product stream into at least a first intermediate productstream comprising the fluorinated alkene of Formula I and thefluorinated alkane of Formula II and a second intermediate productstream comprising the fluorinated alkene of Formula I and thefluorinated alkane of Formula II; d. adding the fluorinated alkene tothe first intermediate product stream and recycling the firstintermediate product stream to step b; and e. hydrogenating the secondintermediate product stream in a second reactor to produce a finalproduct stream.
 2. The method of claim 1 wherein said reducing agent isH₂.
 3. The method of claim 1 wherein step b results in a percentconversion of the fluorinated alkene in the starting material feedstream of between about 25 wt. % and about 75 wt. %.
 4. The method ofclaim 1 wherein step b results in a percent conversion of thefluorinated alkene in the starting material feed stream of between about45 wt. % and about 55 wt. %.
 5. The method of claim 1 wherein the finalproduct steam comprises less than 20 ppm of the fluorinated alkene offormula I.
 6. The method of claim 1 wherein the final product steamcomprises less than 200 ppm of the fluorinated alkene of formula I. 7.The method of claim 1 wherein said fluorinated alkene of formula Icomprises hexafluoropropylene or 1,2,3,3,3-pentafluoropropene.
 8. Themethod of claim 1 wherein said fluorinated alkane of formula IIcomprises 1,1,1,2,3,3-hexafluoropropane or 1,1,1,2,3-pentafluoropropane.9. The method of claim 1, further comprising dehydrohalogenating saidfinal product stream to produce a second fluorinated olefin of formulaI.
 10. The method of claim 9, wherein the second fluorinated olefin offormula I has one less fluorine atom that the fluorinated olefin of stepa.
 11. The method of claim 1, wherein the hydrogenating step (b) occursin the presence of a I catalyst selected from the group consisting of Pdon carbon, Pd/α-Al₂O₃, Ni/C, and Ni/Al₂O₃.
 12. The method of claim 1,wherein the hydrogenating step (e) occurs in a liquid phase reaction.13. The method of claim 12, wherein the hydrogenating step (e) occurs inthe presence of a catalyst selected from the group consisting of Pd oncarbon, Pd/α-Al₂O₃, Ni/C, and Ni/Al₂O₃.
 14. A method for producing afluorinated alkane comprising: a. providing a starting material streamcomprising hexafluoropropene and 1,1,1,2,3,3-hexafluoropropane; b.hydrogenating the starting material stream with a reducing agent in aliquid phase reaction in a first reactor such that at least a portion ofsaid hexafluoropropene is converted to 1,1,1,2,3,3-hexafluoropropane andto produce an intermediate stream comprising hexafluoropropene and1,1,1,2,3,3-hexafluoropropane, wherein the selectivity of the conversionto said 1,1,1,2,3,3-hexafluoropropane is at least about 80 wt %; c.separating a portion of the intermediate product stream into at least afirst intermediate product stream comprising hexafluoropropene and1,1,1,2,3,3-hexafluoropropane and a second intermediate product streamcomprising hexafluoropropene and 1,1,1,2,3,3-hexafluoropropane; d.adding hexafluoropropene to the first intermediate product stream andrecycling the first intermediate product stream to step b; and e.hydrogenating the second intermediate product stream in a second reactorto produce a final product stream.
 15. A method for producing afluorinated alkane comprising: a. providing a starting material streamcomprising 1,2,3,3,3-pentafluoropropene and1,1,1,2,3-pentafluoropropane; b. hydrogenating the starting materialstream with a reducing agent in a liquid phase reaction in a firstreactor such that at least a portion of said1,2,3,3,3-pentafluoropropene is converted to1,1,1,2,3-pentafluoropropane and to produce an intermediate streamcomprising 1,2,3,3,3-pentafluoropropene and 1,1,1,2,3-pentafluoropropanewherein the selectivity of the conversion to said1,1,1,2,3-pentafluoropropane is at least about 80 wt %; c. separating aportion of the intermediate product stream into at least a firstintermediate product stream comprising 1,2,3,3,3-pentafluoropropene and1,1,1,2,3-pentafluoropropane and a second intermediate product streamcomprising 1,2,3,3,3-pentafluoropropene and1,1,1,2,3-pentafluoropropane; d. adding 1,2,3,3,3-pentafluoropropene tothe first intermediate product stream and recycling the firstintermediate product stream to step b; and e. hydrogenating the secondintermediate product stream in a second reactor to produce a finalproduct stream.